Police say the launchers appear to be antitank weapons. Authorities collected more than 2,000 weapons in exchange for supermarket gift cards.

Two rocket launchers turned in to the Los Angeles Police Department as part of the city's gun buyback event appear to be antitank weapons from the military, experts said.

Police said the people turning them in at the buyback told officers they had family members who were at one time in the military and "they no longer wanted the launchers in their homes."

Several military experts said one of the weapons was probably a version of the AT4, an unguided antitank weapon. It's a single-shot weapon that a soldier fires and then the tubing is discarded.

The two launchers — long metal tubes that were once capable of propelling rocket grenades — were turned in along with 2,037 weapons at a gun buyback Wednesday, and exchanged for supermarket gift cards.

Det. Gus Villanueva said the launchers were "stripped-down shells" without the technical parts needed to discharge a projectile. "They don't have capability to discharge anything anymore," he said.

Los Angeles police gun experts will be checking the origins of these weapons with the U.S. military to see if they were ever stolen, he said.

Villanueva said officers could not provide details on the models.

Among the 2,037 firearms were 75 assault weapons, officials said. The total was nearly 400 more weapons than were collected in a similar buyback earlier this year.

Police Chief Charlie Beck said he's used to military-style weapons being turned in at such events. He noted that neither of the launchers had rockets in them, and they did not pose a danger.

Still, he said assault weapons have no place on the streets of L.A.

"Those are weapons of war, weapons of death," Beck said. "These are not hunting guns. These are not target guns. These are made to put high-velocity, extremely deadly, long-range rounds down-range as quickly as possible, and they have no place in our great city."

Mayor Antonio Villaraigosa said the collection at two locations was so successful that the city ran out of money for supermarket gift cards and got a private donation through the city controller to replenish the pot.

The gun buyback was moved up from its usual Mother's Day date in response to the massacre Dec. 14 that claimed the lives of 26 people, including 20 students at Sandy Hook Elementary School in Newtown, Conn.

"As you can see to my right and left, these weren't just guns that weren't functioning anymore," Villaraigosa said at a news conference Thursday morning. "These were serious guns — semiautomatic weapons, guns that have no place on the streets of Los Angeles or any other city."